Burglar alarm



April l' 1945., o. L. scHRlNER 2,374,139

BURGLAR ALARM I Filed July s, 1941 WITNESSES: INVENTOR. v

Patented Apr. 17, 1945 .-muriel). sourires PATENT orificev BURGLAR ALARMp oliver L. sommer, Attica', Y.; Appiicatn .my 3, 1941, serial No.1p1-,oso

(c1. zoo-52) '-.Thisinvention relates to a burglar alarm and has forlan'object to providev essentially a circuit closer formed' of nestedmetal pipes insulated from .each other and adapted to closea circuit toielectrically voper-ated alarm devices when an attempt is made to sawthrough the pipes,- the pipes beingadapted to form a closure foropenings to be protected 'as well as to forman inclosure for localities'to be protected.

A lfurther object is to provideaburglar alarm of this character whichwill be operated by direct current in the event of failure of the normalalternating current due to tampering orsome other causes. Y

A further` object is to provide apparatus of this character which willbe formed of a few strong, simple and durable parts, which will beinexpensive to manufacture, and which will not easily get out of order.

With the above and other objects in view the invention consists ofcertain novel details of construction and combinations of partshereinafter fully described and claimed, it being understood thatvarious modifications may be resorted to within the scope of theappended claim without departing from the spirit or sacrificing any ofthe advantages of the invention.

In'the accompanying drawing forming a part of this specification:

Figure 1 is a fragmentary front elevation with parts in section, showinga burglar alarm circuit closer constructed in accordance with theinvention and' showing the electrical connections thereof with alarmdevices.

Figure 2 is a detail longitudinal sectional view points. The outer pipehas its ends extended through and welded to a hollow metal frame inucluding upper and lower bars I3 and I4, and end bars I5, one of which isshown. The bars of the frame constitute a ground as well as a mountingto dispose the bars I0 to form a closure for an opening to be protected,or to form an inclosure for a, locality to be protected.

- upper vend of the outer pipe H.

The inner pipes I2 are supported in spaced relation to the outer pipesby lower, upper', and in some cases intermediate insulators i6, II andI8 respectively. The lower insulator is supported Within the lower endofthe outer pipe by a metal cap I9 which is screwed on to said end ofthe pipe and then welded't'o the bottom metal bar I4. The upper endofthis insulator is reduced as shown at 2U and extends into the lower endof the inner pipe I2.

The upper insulator Il surrounds the upper end 0f the inner pipe I 2 andextends into the It is secured in place by a flange 2I which overlapsthe upper end of the outer pipe I I. The intermediate insulator I8, whenused, is of annular form and surrounds the inner pipe as well ascontacts with the inner. surface of the outer pipe. The intermediateinsulator is held in place by screws 22 which are threadedly engaged inthe inner pipe above .and below the insulator and have their headsengaging with the top and the bottom of the insulator, see Figure 2. Thepipes I0 and II form terminals of a circuit closer when a surreptitiousattempt is made to saw through the pipes, the hack saw Aformingrbridging contact between the terminals during the sawing operation.

The bars III are wired for both direct and alternating current and forthis purpose a circuit wire 23 is trained through the frame formed bythe hollow bars I3 and is bared of insulation at spaced points andwelded, or otherwise electrically connected, to the projecting upperends of the inner pipes I2, as shown in Figure 3. The wire is connectedto a signal wire 24 which is connected to one terminal of an alarmdevice such as an electric bell 25. The `other terminal of the alarmdevice is connected by a signal wire 26 and armature 35 to one terminalof the secondary coil 2'I of a step down transformer, the primary coil28 of which is connected to supply wires 29 from an alternating sourceof current.

When the outer pipe Iis sawed through and the hack saw touches the innerpipe the alarm circuit will be closed, and may be tra-ced from thesecondary coil 2l of the transformer through the alarm device 25, to thesignal wire 24, thence to the conductor wire 23 through the inner pipeI2 to the outer pipe II and to the hollow bar I4 which is grounded asshown at 3l.

Should the alternating source of supply fail, it is desirable thatstorage battery current be used to operate the burglar alarm when asurreptitious attempt is made to cut through the bars I0.

For this purpose a storage ibattery 32 is connected by conductor wire 33to one terminal 34 of a switch of which this spring retracted armature35 forms a part. The other terminal 34a of the switch is connected by aWire 36 to one terminal of the electric bell 25a. It will be pointed outthat when the alternating source of supply is in operation the step downtransformer functions as a relay which coacts with the armature 35 tohold the direct current line, which is traced, open at the terminals 34and 34a but when the alternating source of supply fails the transformerbecomes dead and the controlling spring of `the armature 35 closes thedirect current line at the terminals 34 and 34a. l

To complete the directed alarm circuit a signal wire 31 is connected tothe other terminal of the alarm device 25a and is connected to a circuitwire 38 which is trained through the frame formed by the hollow bars I4,I and I3 and isconnected at intervals to conductor wires 39 which passthrough the bottom insulators I8 andare trained axially upward in theinner pipes I2.

kThe upper end of each wire 39 is secured in place by an insulator 40which snugly ts within the inner pipe I2. When the alternating source ofcurrent fails the direct current circuit is closed by the circuitclosure formed by the inner pipe and the axial wire 38 after both pipeshave been sawed through. The direct current circuit may b e traced fromthe batteries 32 to the wire 33, armature 35, wire 36, alarm'device 25a,wire 31, wire 38, axial wire 39, and grounded outer pipe I I.

From the above description it is thought that 'having upper end lowersides in which the bars are mounted, the ends of the outer pipesextending through and welded to said sides of the frame to electricallyconnect the outer pipes thereto, the lower ends of the inner pipesterminating short of the corresponding ends of the outer pipes and ltheupper ends of the inner pipes extending above the corresponding ends ofthe outer pipes, lower and upper insulators spacing the inner pipes fromthe outer pipes, metal caps supporting the lower insulators within theouter pipes, the caps being screw threaded on the lower ends of theouter pipes and welded to the lower side of the frame, the upper ends ofthe lower. insulators being, reduced and extending into the lower endsof the inner pipes,v the upper insulators extending-into the upper endsof the outer pipes in surrounding relation to the upper ends of theinner pipes, an insulated conductor housedk within the frame andelectrically connected to the extended upper ends of the inner pipes, asecond insulated conductor housed within the frame, and conductorslocated axially within the inner pipes and extending through said lowerinsulators, said conductors having their lower ends connectedelectrically to said second conductor and having their upper endsinsulated from the inner pipes.

OLIVER L. SCHRINER.

